Applicability of time average geometric moire for vibrating elastic structures

Abstract

Time average geometric moire´ for analysis of in-plane vibrations of elastic structures is proposed in this paper. The intensity of the higher fringes is blurred, which hides this method among other non-contact whole-field experimental techniques for analysis of structural vibrations. This paper proves that such a method is feasible for the analysis of vibrations. It has many advantageous features and is a straightforward method that does not require a complex experimental set-up. It is even simpler than double exposure geometric moire´ since no artificial superposition of the reference image and the image of the object in the deformed state is necessary. Naturally, the interpretation of fringe patterns in time average geometric moire´ is different from the double exposure geometric moire´. But this fact does not lessen the practical value of the method, which can be effectively exploited for analysis of vibrating elastic structures.